Fair value measurements - Investments in Company-Sponsored Funds (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Investment Holdings [Line Items]
Fair Value	$ 8,795	$ 5,521
Unfunded Commitments	3,018	4,035
Hedge Funds
Investment Holdings [Line Items]
Fair Value	574	900
Unfunded Commitments	$ 0	$ 0
Hedge Funds \| Minimum
Investment Holdings [Line Items]
Redemption notice period	30 days	30 days
Hedge Funds \| Maximum
Investment Holdings [Line Items]
Redemption notice period	120 days	120 days
Private Equity Funds
Investment Holdings [Line Items]
Fair Value	$ 8,221	$ 4,621
Unfunded Commitments	$ 3,018	$ 4,035

Investment redemption notice period minimum.

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- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=SL6742756-110258

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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